Aspects of the disclosure relate to measuring the performance of call completion in wireless communications systems.
In wireless telecommunication devices, such as cellular phones, PDAs, mini-laptops, and advanced pagers, the devices typically communicate over long distances by bridging telephone calls through existing cellular telephone networks and passing data packets across the network. These wireless devices have varying data processing and computing capability, and can accordingly send and receive software programs, in addition to voice, across the wireless network.
One wireless telecommunication service provides a quick one-to-one or one-to-many communication that is generically referred to as “Push to talk over cellular” (“PTT PoC,” “push to talk,” “PTT”) capability. The specific PTT group of recipient devices for the communicating wireless device is commonly set up by the carrier. A PTT communication connection is typically initiated by a single button-push on the wireless device that activates a half-duplex link between the speaker and each member device of the group so that the wireless device can speak on the “floor” and once the button is released, the floor is released and the wireless device can receive incoming PTT transmissions. In some arrangements, the PTT speaker will have the “floor” where no other group member can speak while the speaker is speaking. Once the speaker releases the PTT button, any other individual member of the group can engage their PTT button and they will have the floor.
In a PTT environment, when the PTT server sends an ANNOUNCE message to a target client, the packet data serving node (“PDSN”) receives the ANNOUNCE message and needs to route that message to the target client's wireless communication device. In order to route the ANNOUNCE message to the appropriate radio access network (“RAN”), the PDSN must have an established A10 connection with the RAN. It is possible that the PDSN receives the ANNOUNCE message for a target device without having an established A10 connection with the RAN. This can occur because, due to an internal problem at either the RAN or PDSN, an A10 or point-to-point protocol (“PPP”) connection between the RAN and PDSN is not present for the target client device. In current systems, the PDSN will drop the announce message, the PTT server will time out, and will keep resending the ANNOUNCE message according to a preset reliability mechanism. After the reliability mechanism has completed, the server will end the call and send a STATUS failure message to the operator indicating that the target device cannot be reached. There may be several issues associated with this design.
First, the current system may waste server resources to retry the ANNOUNCE message. Second, it may waste over-the-air bandwidth resources for the originating wireless communication device, because the server does not send the STATUS failure before it exhausts the reliability mechanism. Third, in current systems, one cannot infer whether the message reached the target RAN or not from the cause code of the STATUS failure or from the server log. Fourth, during field testing activity when the only logs available are client logs, it is very important to know the exact failure code for the failed call attempt. A generic failed reason of “target unreachable” does not help identify the root cause of the problem.
Similar issues may occur in other wireless communications systems that utilize multiple bearers for communications between a device and network having an evolved packet core (EPC). In such systems, an application server providing voice services can send a call setup message to a serving node in the EPC to establish a call from an originating device to a target device. Though the EPC may have a default bearer to the target device, it may not have a bearer capable of providing a quality of service (QoS) for the voice services. Thus, the EPC may attempt to setup the call over a bearer that does not meet QoS requirements for the call. In other cases, the EPC may drop the call setup message due to lack of a dedicated bearer, which may cause the application server to timeout and repeatedly resend the call setup request. Moreover, in some examples, such as in voice over long term evolution (VoLTE), upon receiving a call setup failure, the originating wireless communication device may fall back to a circuit switch voice call technology (e.g., code division multiple access (CDMA), global system for mobile communications (GSM), etc.).
As such, it would be beneficial to have techniques that increase the speed and minimize the resources involved with communicating a call failure message to an originating wireless communications device.